1. Field of the Invention
The present invention relates to a subminiature imaging optical system, and more particularly, to subminiature imaging optical system installed in a mobile communication terminal and a personal digital assistant (PDA) to increase resolution at a peripheral portion and decrease distortion for better resolution, maintains lens shape and optical properties stably even in a high temperature assembly process, and effectively block incidence of a light portion outside an effective angle of view to improve axial aberrations and be manufactured at a low cost.
2. Description of the Related Art
In general, mobile communication terminals had only functions of basic communication at their incipient stage. However, with increased use, the mobile communication terminals are required to have diversified functions ranging from photographing to image transmission and video communication, continuously evolving in their functions and services. Recently, a new expanded concept of mobile communication terminal by integrating digital camera technology with mobile phone technology, i.e., so called camera phones or camera mobile phones are significantly attracting attention.
In particular, the imaging optical system mounted on the camera phone is not only required to be miniaturized, light-weight and low-cost, but also have high resolution since the pixel size of an image sensor formed of a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) used in the imaging optical system is decreasing.
In order to satisfy miniaturization and low cost, the imaging optical system mounted on a small device such as a mobile phone needs to have lenses of as small a number as possible, but this restricts a degree of freedom in designing and undermines the optical capabilities.
Especially, in the conventional imaging optical system, an aperture stop is disposed in an area other than lenses to adjust a light amount, thereby hindering reduction in size and weight of the optical system.
Therefore, there is a demand for a subminiature imaging optical system which can be reduced in size and weight, while having high resolution and excellent aberrational characteristics.
Moreover, when the imaging optical system is assembled at a high temperature to be employed in a camera module having the image sensor mounted thereon, the lens made of plastic is altered in shape and accordingly optical properties, thereby degrading optical properties of the camera module.